html{
    font-size: 10px;
}
html,body{
    margin: 0;
    padding: 0;
    font-family: sans-serif;
}
.keys{
    display: flex;
    min-height: 100vh;
    justify-content: center;
    align-items: center;
}
.key{
    border-radius: 0.5rem;
    border: 0.4rem solid #000;
    margin: 1rem;
    width: 10rem;
    font-size: 1.5rem;
    padding: 1rem 0.5rem;
    text-align: center;
    background: rgba(0,0,0,0.4);
    color: #fff;
    text-shadow: 0 0 0 0.5rem #000;
}
.key > div{
    font-size: 4rem;
}
.sound{
    font-size: 1.2rem;
    text-transform: uppercase;
    letter-spacing: 0.1rem;
    color: #ffc660;
}